Recent content by Kane O'Donnell

I should point out here that although almost everyone does use the WKB approximation in these cases, there has been a bit of a move in recent times to be more cautious in the application of the FN equation to arrays of emitters. Look at K Jensen's papers on FE - see especially his chapter in...

No, I'm not saying time is infinite in both forward and backwards directions, all I'm saying is that just because something is infinitely long doesn't mean it has to start somewhere. It's just mathematics, don't read too much into it. This makes no sense. It's like saying just because there...

Not true, consider the set of integers - it goes to infinity in both directions, position and negative, so it doesn't have a start. No matter where you choose the start to be, there are an infinite number of smaller numbers and an infinite number of bigger ones. We don't know. At this stage...

Whoops, don't mind me, you're after a different kind of translation. :smile: Still, the above method does seem rather complex for what isn't a particularly difficult problem - if I remember correctly you can do it crudely by transforming the Schroedinger equation and then finding a phase...

Seems like a fairly odd way of going about finding these translations. If I remember correctly, for the free-particle non-relativistic hamiltonian the generators of the translation are just the components of the momentum operator, you can show this in a fairly straightforward manner by using the...

Also, treating E = mc^2 as a conversion equation is a little bit more subtle. As dlgoff has already pointed out, it's a reduced form of the more general equation in the case when the object with mass m is at rest. What E = mc^2 says is, if we ignore potential energy, an object with no kinetic...

Well, sorry to jump in late, but a state space is a Hilbert space, which is a complete inner product space. An inner product space is a vector space, which is, amongst other things, defined in terms of it's group structure. So at this rudimentary level, yes, you should have *seen* some group...

Nope, we don't. I should probably get the Physics Society here to buy a copy if it's that good :smile: Kane

Dude, you *love* that book! This is like the hundredth thread you've mentioned it in! I'm starting to wish we had a copy at Newcastle. Kane

Has anyone mentioned Liboff yet? Only a mid-level text, but very good. It's the recommended reference for our 2nd year QM course here at Newcastle, although after first year none of the courses have fixed texts.

To add to what I just said, XPS is practically just a photoelectric experiment, because all you're doing is shooting X-rays at a target made of anything and measuring the kinetic energy of the ejected photoelectrons. Kane

XPS works for basically any element except He, H. Obviously this is because X-rays have a hellofalot of energy. :smile: Kane

I should point out though, with nanotubes, typically what you do is form them on some larger surface area (via chemical vapour deposition or whatever) and then deal with lots of nanotubes emitting instead of just trying to deal with one individual one. I work with single-walled CNTs so I...

Well typically the 'working end' of a FE tip is of the order of 10s of nanometres in diameter, so yes, they're very small! :smile: On the other hand, the tip itself is often sharpened or etched from a larger piece of wire, for example the Tungsten wires in my experimental apparatus start off...

The process you have described is thermionic emission of electrons from some filament (usually tungsten or something involving tungsten because of it's high melting point). With nanotubes, we are interested in a phenomena called field emission, where electrons, instead of just stepping over...